Adhesives are widely used in the liquid crystal display (LCD) products for bonding parts and sealing. The LCD products include digital products such as mobiles, televisions, laptops, PC and the like.
UV-radiation curable adhesives, thermal-curable adhesives and moisture-curable adhesives are now known in the art.
As an example of the moisture-curable adhesives, U.S. Pat. No. 7,060,750 B2 discloses moisture-curable polyether urethanes and their use in sealants, adhesives or coating compositions. Specifically, the sealants, adhesives or coating compositions disclosed in U.S. Pat. No. 7,060,750 B2 comprise three components: a) 20 to 80 wt. % of a polyether urethane containing two or more reactive silane groups and one or more polyether segments; b) 20 to 80 wt. % of a polyether urethane containing one reactive silane group and one or more polyether segments; and c) 1 to 60 wt. % of a pigment having a BET surface area of from 15 to 100 m2/g and an oil absorption of from 40 to 110 cc/100 g.
As an example of the thermal-curable adhesive, U.S. Pat. No. 6,617,371 B2 discloses a single component room temperature stable thermal-curable (meth)acrylate resin adhesive, comprising: about 5 to about 70 wt. % of at least one (meth)acrylate monomer; about 5 to about 94 wt. % of a (meth)acrylate oligomer; and about 0.1 to about 10 wt. % of a thermal initiator selected from the group consisting of diacyl peroxides, benzoyl peroxides and peroxyesters.
Up to now, there is however no report on the adhesive curable by the three ways, especially the adhesive that is curable by the three ways and suitable to be used in the LCD products. For an adhesive to be used in the LCD products, it is usually desired that the cured products thereof have a high transparency.
At present, there are many deficiencies as to the adhesives used in the assembly of LCD panel and as to the assembling processes. For example, shadow areas exist at edges of LCD panel or at regions covered by PCB and the like, under the condition of photo curing, the adhesive in these shadow areas can not be cured, and hence, an unfirm bonding may be resulted. If the uncured adhesive diffuses to the display area, it may cause corrosion and failure of the display area.
The three curing ways of UV-curing, thermal-curing and moisture-curing each have their own properties and deficiencies. The time experienced in the UV-curing is the shortest, but the UV-curing has high requirements for the devices, and uncured adhesives may remain in the shadow areas. The time experienced in the thermal-curing is longer than that in the UV-curing, but the thermal-curing is not suitable for bonding and sealing precision parts sensitive to heat. The moisture-curing has low requirements for the device, but experiences a relatively long curing time.
Therefore, there exists need for developing an adhesive that can be cured by any one way of UV-curing, thermal-curing and moisture-curing. Ideally, such an adhesive also has a high transparency.